Don't worry, most monitors are able to handle my VSync manipulation routine (I switch refresh rates several times per frame, so the monitor loses vertical sync and you see that scrolling effect). And flashing is harmless. At least for your hardware.

Gargaj,
a) because monitors are quite desperate to decode the sync signal and heavy changes in the picture will fool them. The change is from the forst visible rasterlnie on -> go figure
b) the noise "filter" is in fact "analog" by modifying the CRTC registers in a quite strange way. As all modern graphics cards are designed ti be VGA compatible without any overhead, those registers work even on GF4s and such - and it's no problem to access them directly (win9x) or via undocumented IOPM management routines in the NT kernel - go search for the "portmap" driver to find a description. Anyway. With careful modification of some CRTC registers you can modify the RGB output lines a bit - and that's why the noise is visible even in the VSync blank period. period.
c) under D3D, Windows doesn't have access to the frame buffer. Thus, it uses some strange method for back-sampling the CRT signal via some mostly undocumented A/D and bus mastering circuits. At least on NVidia cards, which I assume you have. That way, it will sample x lines from a VSync on, where x is the actual nubmer of lines. D3D screen shots may look pixel perfect, but they arent - hey, LCD displays work, why not that :)

at least i have access to the framebuffer and do not need this A/D :) to convert back, which of course makes a very subtle but noticeabl difference which once again proves opengls superiority even with simple screenshots :P

OK, last rant: My monitor does this wobble effect (it shows a dim, vertically stretched picture for a few seconds) after every damn modecnahge, refreshchange, vsync, anything... Haven't appeared during this demo tho...

The wobble-effect only occurs when the monitor settings change in such a severe way that the monitor needs to realign all the internal circuitry and so on and so forth. Handling vsync changes (like in kb's effect) would also normally result in such behaviour, but since the changes are so minimal the monitor is still able to maintain sync and keep showing you the picture (although it still 'messes up' the vertical position, but that was the intention of the effect).

-quite nice music
-like the green line stuff
-bit boring after a while

Love the use of VSync modifications to make the scrolly effect, even tho its the kinda thing used on those Japanese cartoons tht have now been banned ;) Nice anyway, hope it doesnt damage my monitor (I assume it hasnt been tested for monitor damage)

"at least i have access to the framebuffer and do not need this A/D :) to convert back, which of course makes a very subtle but noticeabl difference which once again proves opengls superiority even with simple screenshots :P"

major respect for making those vsync hacks so compatible! i've yet to see the system that doesn't display them properly. for once, a really oustanding use undocumented api's and blabla :)
music rockz
(i'd rather leave the visuals undocumented)